Oral bacteria are known to cause various diseases or disorders of the oral cavity, including dental caries, periodontal diseases such as gingivitis and periodontitis, plaque, oral malodour and halitosis. Oral bacteria, and the chronic inflammation of oral tissues which they cause, have also been implicated in a number of systemic diseases, including cardiovascular diseases.
It is therefore desirable to provide oral care compositions comprising antibacterial agents. Many antibacterial agents have been utilised previously, with varying degrees of success. Zinc compounds, in particular zinc oxide, have shown significant promise. In addition to their antimicrobial properties, zinc compounds can fight plaque, prevent calculus formation and reduce mouth malodour. Zinc compounds have also been used in the treatment and prevention of other oral conditions such as pyorrhea and tooth hypersensitivity.
In spite of these promising properties, the use of zinc in oral care compositions has nevertheless been limited. Many antimicrobial zinc compounds, and in particular zinc oxide, suffer from poor aqueous solubility. This restricts the range of formulations into which the zinc compounds of the prior art may be incorporated. Poor solubility may lead to difficulties in achieving a uniform product during the manufacture of oral care formulations. There is therefore a need in the art for zinc compounds with improved solubility.
It is generally desirable to provide antimicrobial ingredients with high potency. Potency may be quantified by minimum inhibitory concentration (MIC) measurements. The MIC is the minimum concentration needed to produce a biocidal or biostatic effect. As zinc has been reported to have undesirable organoleptic properties and can cause mouth irritation, there is a need in the art for zinc compounds with improved potency to allow lower dosages of zinc to be used whilst maintaining the useful functionality of the zinc.